USD plugin issue

[ruby sluice]

Hi !
First to give you some info about me, then I will explain my problem.

• I'm a stil a student (video game Master in France, last year of school)
• I'm an apprentice (?, work-study student ? don't know how it's called in english, but in french it's "alternant") in a compagny, in the automotive industry
• I'm kind of alone in development (for now at least... I hope....) and I'm working on really technical things (our use cases are quite complex, especially for me because I'm still Learning, and using things I didn't know existed, and are Learning them.)
• I'm using Metahumans, Sequencer, USD, and many more things which I will need as I get new tasks.......
• I'm using Unreal 5.6.1 (from launcher)

So... I'm working on something with Metahumans and USD. I may need some help some other time with things regarding Metahumans, but for now it's only for the USD plugin.
First, my problem : I can't get a USD file to load AT RUNTIME IN A SHIPPING BUILD (important !!).

Now for more explanations :
First, I want to import into an app (shipping build) a USD file to see it working. For reference, I use the three USD files from pixar's (https://openusd.org/release/dl_downloads.html#assets).
I checked the "documentation" for runtime USD (https://dev.epicgames.com/documentation/en-us/unreal-engine/universal-scene-description-in-unreal-engine#usdruntimesupport) and did as instructed. Added the pugin (USD Core, USD Importer), and set root layer (with the absolute path) to the USD file in the level's begin play for the USD Stage Actor. I also added the FORCE_ANSI_ALLOCATOR to the build.target.cs. This was done in the 5.6.1 from the launcher. I can't remember if it worked, but anyway, when built in shipping mode, it didn't show anything. I didn't have the logs enabled at this point in time, so I could check if the USD plugin was used.

So then, I checked the forum for more informations, and I saw all this :

• https://dev.epicgames.com/community/learning/knowledge-base/jB8v/unreal-engine-usd-ue-format-support
• https://forums.unrealengine.com/t/has-anyone-actually-got-usd-to-work-at-runtime-on-a-packaged-build/1933902/6
• https://forums.unrealengine.com/t/usd-runtime-import-not-working/274652/6
• https://forums.unrealengine.com/t/runtime-usd-loading-behaving-like-editor-import-expected-or-regression/2679470
• https://forums.unrealengine.com/t/ue4-27-runtime-usd-import/487753

There is some questions I asked on some discussions (my pseudo is SixelA_EG).
So the conclusion after reading all this was that I needed to use unreal's source code from github, which I did use.

BUUUUT !!!!! As it was said is some posts in those discussions, some version from source code don't work. And some I couldn't compile at all, as the UnrealEditor.exe was not even present (even after Setup.bat and GenerateProjectFile.bat)..... It was on source code 5.6.1 if I remember correctly.

I managed to build unreal source code, and create a project with the USD plugins for 5.6.0 and 5.7.2. Tried with some others, but not all. Right now, I'm testing for 5.6.0.

Here is a video and the log associated with it. But to summarize, here is the error :
LogUsd: Warning: Discarding StaticMesh generated for prim 'path/to/something' as it didn't produce any valid RenderData (likely all triangles were degenerate)

Here is the entire project to download (test project, same as the video) :
https://www.swisstransfer.com/d/311052cc-b6c6-4485-a628-092e1c865238

Does anyone know how to make this work ?
It needs to be at runtime, and I need to be able de import, and export. For the export, I was not told by my superior if the global scene (anim, mesh, level sequence) needs export, or only some specific meshes. But I do know animations will need to be included.